working with filestreams

#include <fstream>
#include <vector>

//This program demonstrates using ifstream and ostream objects.
//It opens a file with purely numeric input, separated by spaces, then
//loads them into a vector, increments them, and overwrites the file
//with new data formatted into three columns.

int main()
{
  std::ifstream readFile("Text.txt");
  std::vector<int> vec;
  int temp;
  while(readFile >> temp)
  {
    vec.push_back(temp);
  };
  readFile.close();

  for (auto& i : vec)
    ++i;

  std::ofstream writeFile("Text.txt"); //overwrites contents!
  for(unsigned i = 0; i < vec.size(); ++i)
  {
    writeFile << vec[i] << ' ';
    if ((i + 1) % 3 == 0)
      writeFile << '\n';
  }
  writeFile.close();
}

/* Contents of "Text.txt":
0 0 0
1 1 1
2 2 2
3 3 3
4 4 4
*/